Method for fabricating semiconductor device
A method for fabricating a semiconductor device on a semiconductor substrate, wherein the semiconductor device is adapted to provide target lasing properties, the method includes creating, a mask layer over the semiconductor substrate, the mask layer having at least one opening to expose a region of the semiconductor substrate, etching using a first etching process the exposed region, utilizing inductively coupled plasma with preselected first set of parameters to obtain a baseline mesa profile, the baseline mesa profile having a baseline mesa angle, re-etching using a second etching process the etched region, utilizing inductively coupled plasma with preselected second set of parameters, to alter the baseline mesa profile to obtain a requisite mesa profile having a requisite mesa angle defined by the target lasing properties and the requisite mesa angle being different from the baseline mesa angle, removing the mask layer and defining a p-n junction for the semiconductor substrate.
1. A method for fabricating a semiconductor device on a semiconductor substrate, the method comprising:
creating, a mask layer over the semiconductor substrate, the mask layer having at least one opening to expose a region of the semiconductor substrate;
etching the exposed region using a first etching process utilizing inductively coupled plasma with a preselected first set of parameters to obtain a baseline mesa profile, the baseline mesa profile having a baseline mesa angle;
re-etching the etched region using a second etching process utilizing inductively coupled plasma with preselected second set of parameters, to alter the baseline mesa profile, the second set of parameters being different from the first preselected parameters, to obtain a requisite mesa profile having a requisite mesa angle different from the baseline mesa angle;
removing the mask layer; and
defining a p-n junction for the semiconductor substrate,
wherein the preselected first set of parameters comprises utilizing the inductively coupled plasma for the first etching process which is denser compared to the inductively coupled plasma utilized as part of the preselected second set of parameters for the second etching process.
2. The method according to claim 1 , wherein the preselected second set of parameters comprises a preselected etch time for the second etching process, a preselected reactive-ion etching (RIE) power for the inductively coupled plasma and are selected based on the requisite mesa angle.
3. The method according to claim 1 , wherein the second etching process is an anisotropic etching process.
4. The method according to claim 1 , wherein the mask layer is one of a photoresist mask layer or a hard mask layer.
5. The method according to claim 1 , wherein the preselected first set of parameters are selected based, at least in part, to obtain the baseline mesa profile having a predefined depth.
6. The method according to claim 5 , wherein the second etching process is performed to alter a sidewall profile of the baseline mesa profile to define the requisite mesa angle for the requisite mesa profile while, substantially, retaining same depth for the requisite mesa profile as the predefined depth of the baseline mesa profile.
7. The method according to claim 1 , wherein defining the p-n junction for the semiconductor substrate further comprises:
depositing an insulating layer over the semiconductor substrate;
defining an opening in the insulating layer corresponding to a top area of the requisite mesa profile utilizing photolithography techniques;
forming a p-contact at the top area of the requisite mesa profile; and
forming a n-contact on a backside of the semiconductor substrate.
8. The method according to claim 7 , wherein the step of forming the n-contact further comprises heating the semiconductor substrate by rapid thermal annealing.
9. The method according to claim 7 , wherein prior to the step of forming the n-contact, the method comprises thinning the semiconductor substrate.
10. The method according to claim 9 , wherein the semiconductor substrate is thinned to about 200 micrometres.
11. The method according to claim 7 further comprising:
cleaving the semiconductor substrate to define bars; and
coating facets of the defined bars to form mirrors.
12. The method according to claim 11 further comprising:
scribing chips off the formed mirrors; and
mounting the scribed chips to form the semiconductor device.
13. A semiconductor device comprising a p-n junction on a semiconductor substrate, the semiconductor device fabricated by:
creating a mask layer over the semiconductor substrate, the mask layer having at least one opening to expose a region of the semiconductor substrate;
etching the exposed region using a first etching process utilizing inductively coupled plasma with a preselected first set of parameters to obtain a baseline mesa profile, the baseline mesa profile having a baseline mesa angle;
re-etching the etched region using a second etching process utilizing inductively coupled plasma with a preselected second set of parameters, to alter the baseline mesa profile, the second set of parameters being different from the first preselected parameters, to obtain a requisite mesa profile having a requisite mesa angle different from the baseline mesa angle;
removing the mask layer; and
defining a p-n junction for the semiconductor substrate,
wherein the preselected first set of parameters comprises utilizing the inductively coupled plasma for the first etching process which is denser compared to the inductively coupled plasma utilized as part of the preselected second set of parameters for the second etching process.
14. The semiconductor device according to claim 13 , wherein the semiconductor device is a laser device.